copy etcd from images

when server.image is set then binary is copied from docker image

Change-Id: I59c220deabfdf861613f16cf757ba0da44976a9c
diff --git a/tests/pillar/proxy.sls b/tests/pillar/proxy.sls
index b440098..5313ab7 100644
--- a/tests/pillar/proxy.sls
+++ b/tests/pillar/proxy.sls
@@ -1,5 +1,6 @@
 etcd:
   server:
+    image: quay.io/coreos/etcd:latest
     enabled: true
     bind:
       host: 10.0.175.101
@@ -10,4 +11,4 @@
     - host: 10.0.175.102
       name: etcd02
     - host: 10.0.175.103
-      name: etcd03
\ No newline at end of file
+      name: etcd03